Leptochiton cancellatus ( Sowerby, 1840 )

Leptochiton cancellatus ( Sowerby, 1840) View in CoL

Fig. 13 View FIGURE 13

Chiton cancellatus G.B. Sowerby II, 1840 , figs 104, 104a–104b, 105; Reid 1890, tab. 3.

Lepidopleurus ( Leptochiton) cancellatus View in CoL ; Dell’Angelo & Palazzi 1989, p. 58, pls 6–7; Dell’Angelo & Smriglio 1999, p. 48, pls 10–11, figs 18–19; Dell’Angelo et al. 2001a, p. 146, fig. 5; Marquet 2002, p. 12, pl. 2, fig. 1; Dell’Angelo & Silva 2003, p. 9, figs 3–4; Tabanelli 2008, p. 59.

Lepidopleurus ( L.) cancellatus View in CoL ; Malatesta 1962, p. 147, figs 3–4.

Lepidopleurus cancellatus View in CoL ; Marquet 1984, p. 336, pl. 1, fig. 2; Chirli 2004, p. 5, pl. 1, figs 16–18, pl. 2, figs 1–2.

non Lepidopleurus cf. cancellatus View in CoL ; Šulc 1934, p. 6 (= Leptochiton sp. , this study).

? (reported as Lepidopleurus cancellatus View in CoL without description or figures); Brogger 1901, p. 656; Antevs 1917, p. 396–409, 417. Leptochiton ( Leptochiton) cancellatus View in CoL ; Kaas & Van Belle 1985a, p. 43, fig. 16; Dell’Angelo & Palazzi 1986, p. 10, figs 6–8, 41, 51, 65, 67, 69; Cesari 1987, p. 6, pl. 1, figs 1–7.

Leptochiton cancellatus View in CoL ; Kaas 1981, p. 217, figs 10E–F; Macioszczyk 1988, p. 51, pl. 1, figs 6, 7a–b; Sosso & Dell’Angelo 2010, p. 14, unnumbered fig. p. 16; Strack 2010 (cf.), p. 62, fig. 50; Studencka & Dulai 2010, p. 260, text-fig. 2A–D; Dell’Angelo et al. 2012, p. 54, figs 3A–C; Dell’Angelo et al. 2013, p. 70, pl. 1, figs N–T; Dell’Angelo et al. 2015a, p. 226, pl. 3, figs 1–6; Dell’Angelo et al. 2021b, p. 408, figs 14–21; Dell’Angelo et al. 2022, p. 4, figs 3.1–3.9.

Leptochiton cf. cancellatus View in CoL ; Brunetti & Cresti 2018, p. 28, fig. 1; Brunetti & Cresti 2023, p. 10.

non Lepidopleurus cancellatus View in CoL ; Laghi 1977, p. 98, pl. 1, figs 1–3 [= Leptochiton scabridus (Jeffreys) View in CoL , fide Dell’Angelo & Palazzi 1989: 61].

Leptochiton sulci View in CoL [non Leptochiton sulci ( Bałuk, 1971) View in CoL ]; Macioszczyk 1988, p. 51 –52, pl. 1, fig. 8a–b ( fide Studencka & Dulai 2010).

Type material. Unknown , probably lost ( fide Kaas & Van Belle 1985a: 43) .

Type locality. P ossibly the coast of Great Britain, probably Oban , Scotland ( fide Kaas & Van Belle 1985a: 43) .

Material examined. Middle Miocene: Eastern Paratethys: Ukraine: Varovtsi: 7 valves ( BD 351, Figs 13M–P View FIGURE 13 ), Horodok: 12 valves ( BD 352, Figs 13Q–T View FIGURE 13 ). Upper Miocene: Italy: Po Basin: Montegibbio: 2 valves ( BD 353, MZB 32046), Rio di Bocca d’Asino: 8 valves ( BD 354, PG, MZB 32010–32011, Figs 13I–K View FIGURE 13 ), Villa Monti: 1 valve ( MZB 32045). Lower Pliocene: Italy: Liguria: Borzoli: 42 valves ( BD 355), Bussana: 1 valve ( BD 356), Caranchi: 2 valves ( MP), Genova Sestri: 1 valve ( BD 357), Rio S. Antonino: 16 valves ( MP, MZB 45699–45700, Fig. 13L View FIGURE 13 ), Rio Torsero: 1 valve ( BD 358). Pliocene: Portugal: Vale de Freixo: 265 valves ( BD 237, GeoFCUL VFX.03.339, GeoFCUL VFX.03.346, GeoFCUL VFX.03.349, Figs 13E–G View FIGURE 13 , MNHN.F.A81981, RGM.1363997–1363998). Italy: Tuscany: Cetona: 1 valve ( BD 359), Orciano Pisano: 2 valves ( BD 360), Pietrafitta: 4 valves ( BD 361), Pietrafitta Melograni: 4 valves ( BD 362), Poggibonsi: 1 valve ( BD 363), Poggio alla Fame: 3 valves ( BD 364, Figs 13A–D View FIGURE 13 ), Serre di Rapolano: 1 valve ( BD 365); Emilia-Romagna: Cava di Campore: 42 valves ( BD 366), Lugagnano: 4 valves ( BD 367), Rio Stramonte: 2 valves ( BD 368). Upper Pliocene-Pleistocene: Italy: Sicily: Altavilla: 8 valves ( AG, AR, BD 369). Pleistocene: Italy: Tuscany: Caletta: 2 valves ( BD 370); Calabria: Carrabbati: 4 valves ( BD 371), Torrente Boscaino: 1 valve ( BD 372), Vallone Catrica: 1 valve ( BD 373); Sicily: Salice: 5 valves ( BD 374, Fig. 13H View FIGURE 13 ), Sciacca: 1 valve ( BD 375). Maximum width of the valves: 2.5 / 3.4 / 3.8 mm.

Description. Valves thin and fragile. Head valve less than semicircular, posterior margin widely V-shaped, front slope straight. Intermediate valves broadly rectangular (W/L = 2.38–3.23), moderately elevated (H/W = 0.30–0.44), rounded in anterior profile, anterior margin slightly convex, side margins slightly rounded, posterior margin about straight, apex not indicated, lateral areas raised, mostly with a few more or less prominent growth ridges. Tail valve semicircular (W/L = 1.55–1.90), anterior margin straight to slightly convex, mucro subcentral, swollen but not prominent, antemucronal slope slightly convex, postmucronal slope slightly concave.

Tegmentum rough, space between striae of granules reduced, growth lines barely noticeable. HV, LA and PMA sculptured with dense oval granules united, arranged in radial series (HV ca. 50–60, LA ca. 10). CA and AMA sculptured with roundish granules united, partially overlapping, arranged in longitudinal series (CA ca. 60). Each granule with a central megalaesthete and a series of micraesthetes (normally 6–7) rather regularly spaced all along, except on upper side.

Articulamentum without insertion laminae, apophyses small, well separated by a slightly concave jugal sinus, triangular but tending to be trapezoidal in tail valve.

Remarks. Most of the records of small Mediterranean Leptochiton collected at depth between 30 and 100 m have been attributed in the past to L. cancellatus ( Dell’Angelo & Palazzi 1986), whereas this species is instead uncommon in the Mediterranean, being found mainly in deep-water detrital bottoms ( Dell’Angelo & Smriglio 1999).

The fossil record of Leptochiton cancellatus is scant; the species is known from a few sites from Miocene, more common from the Pliocene, rarely recorded from the Pleistocene of Italy, and from the North Europe ( Sweden and Norway).

The recent findings of Leptochiton cancellatus from the Paratethys ( Studencka & Dulai 2010; this study, Figs 13M–T View FIGURE 13 ) considerably extend the stratigraphic and geographic distribution of the species.

Leptochiton sulci ( Bałuk, 1971) View in CoL is a similar species described from the Middle Miocene (early Badenian) of the Paratethys ( Poland: Korytnica). It was considered conspecific with L. cancellatus View in CoL by Laghi (1977), Dell’Angelo & Palazzi (1989), Dell’Angelo & Smriglio (1999) and Dell’Angelo & Silva (2003). However the two taxa show marked differences, so we consider the two nominal taxa as different species, following Studencka & Dulai (2010) and Ruman & Hudáčková (2015), as discussed below (see Leptochiton sulci View in CoL ).

There is a great variability in the material examined, especially for the shape of intermediate valves, from W/L = 2.38–2.50 (Recent) to 2.60–2.80 (Paratethys) and 3.05–3.23 (Pliocene of Italy and Portugal).

Comparisons. See Tab. 2 for a comparison with the Leptochiton spp. considered in the present study.

Distribution. Middle Miocene: Central Paratethys (Langhian-Serravallian): Poland: Gieraszowice, Rybnitsa, Węglinek ( Macioszczyk 1988; Studencka & Studencki 1988); Eastern Paratethys: Ukraine: Horodok, Varovtsi ( Studencka & Dulai 2010; this study). Upper Miocene: Proto-Mediterranean Sea (Tortonian): Po Basin, North Italy: Montegibbio, Rio di Bocca d’Asino, Villa Monti ( Dell’Angelo & Palazzi 1989; Dell’Angelo et al. 2015a). Lower Pliocene: North Europe, Belgium: Kallo ( Marquet 1984, 2002); northeastern Atlantic: U.K. ( Reid 1890); central Mediterranean, Italy: Liguria: Borzoli, Caranchi, Rio S. Antonino, Rio Torsero, Sestri Ponente ( Sosso & Dell’Angelo 2010; Dell’Angelo et al. 2013, 2021b); Pliocene: northeastern Atlantic, Mondego Basin, Portugal: Vale de Freixo ( Dell’Angelo & Silva 2003; Dell’Angelo et al. 2022) central Mediterranean, Italy: Emilia-Romagna: Cava di Campore, Lugagnano Val d’Arda, Rio Stramonte (this study); Tuscany: many localities ( Dell’Angelo et al. 2001a; this study): Sicilia: Altavilla Milicia ( Dell’Angelo et al. 2012). Pleistocene: North Atlantic: Sweden and Norway ( Brogger 1901; Antevs 1917), Netherlands ( Strack 2010); central Mediterranean, S. Italy: Carrabbati, Salice, Sciacca, Torrente Boscaino, Vallone Catrica (this study). Recent: Atlantic Ocean: from U.K. and Ireland (McKay & Smith 1979; Light & Baxter 1990) to the coast of France ( Kaas 1979; Dell’Angelo & Palazzi 1986), Spain ( Borja 1987; Rolan Mosquera et al. 1990; Urgorri et al. 2017), Portugal ( Consolado Macedo et al. 1999) and Madeira Arch. ( Segers et al. 2009). Mediterranean Sea: Spain ( Moreno & Gofas 2011); Italy: Gulf of Venezia ( Cesari 1987), Banco Amendolara ( Panetta et al. 1985), Strait of Messina ( Giacobbe & Renda 2018) , Strait of Sicily ( Dell’Angelo et al. 1998a), and many other localities ( Dell’Angelo & Smriglio 1999); Malta ( Mifsud et al. 1990); Greece and Aegean Sea Islands ( Strack 1990; Zenetos & Van Aartsen 1995; Koukouras & Karachle 2005); Turkey ( Ozturk et al. 2014); Tunisia ( Kaas 1989; Cecalupo et al. 2008); Israel ( Barash & Danin 1977); Marmara Sea ( Öztürk et al. 2014).